When a chimney fire occurs homeowners ofter wonder what they should do next, and unfortunately can get bad advise from well-meaning people. The Midwest Chimney Safety Council recommends that the chimney be inspected by a professional chimney sweep before further use of the chimney. It is common for masonry and stainless steel chimneys to be damaged after being exposed to a fire.
After a recent chimney fire at the home of a chimney sweep in Independence, Missouri (see my earlier article on this subject) the sweep inspected the stainless steel chimney pipe serving a wood stove. What he found was surprising - there were no damages to the pipe. The short duration of the fire was no doubt the reason no damages were found. Only discoloration of the chimney pipe occurred. The chimney cover was clogged with an accumulation of burnt creosote which the sweep removed. When creosote burns it expands up to 10 times in size and becomes lightweight with a honeycomb appearance.
If the fire had been longer in duration the pipe may have sustained damages such as buckling, warping, and opening of the seams in the pipe. When this happens the chimney must be replaced since it is no longer safe to use.
In masonry chimneys the damages can be severe. Chimney sweeps often find cracked and broken flue tiles, blown out tiles and mortar joints, and missing mortar in smoke chambers. Severe and long-lasting chimney fires will cause more damages and can crack the exterior masonry chimney or cement crown, or facial wall on the interior. Chimney fire damage can be expensive to repair but can be avoided with regular annual sweeping by a chimney sweep. Wood stove flues should be swept two or more times during the wood-burning season.
The inspection should be completed by a CSIA Certified Chimney Sweep, who is trained to inspect and sweep chimneys and knows the International Residential Code and NFPA 211 Standards for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances.